title: C2-symmetric bisamidines: chiral Brønsted bases catalysing the Diels-Alder reaction of anthrones.
abstract: C(2)-symmetric bisamidines 8 have been tested as chiral Brønsted bases in the Diels-Alder reaction of anthrones and N-substituted maleimides. High yields of cycloadducts and significant asymmetric inductions up to 76% ee are accessible. The proposed mechanism involves proton transfer between anthrone and bisamidine, association of the resulting ions and finally a cycloaddition step stereoselectively controlled by the chiral ion pair.
authors.affiliation: Johann Wolfgang Goethe University Frankfurt, Institute of Organic Chemistry and Chemical Biology, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main, Germany.
authors.forename: Deniz
authors.initials: D
authors.lastname: Akalay
authors.forename: Gerd
authors.initials: G
authors.lastname: Dürner
authors.forename: Jan W
authors.initials: JW
authors.lastname: Bats
authors.forename: Michael W
authors.initials: MW
authors.lastname: Göbel